Slides from LinkedIn's presentation at MongoDB World 2014, description below: LearnIn is LinkedIn’s internal learning platform packed with a huge variety of resources that will help our employees learn, develop, and grow professionally. In this talk, we will discuss how a small team of web developers built this platform’s API using MongoDB and a full JavaScript stack including Node.js. In particular, we will look at schema design and document validation using Mongoose ODM for Node.js, as well as quick document search utilizing MongoDB full-text search and our move to ElasticSearch using the MongoDB oplog.

1. 1

2. Jacob Dejno
Web Developer
Ryan Seamons
Product Manager
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3. We will cover:
• LearnIn, LinkedIn’s Internal Learning Portal
• Using Node.js and MongoDB
• Mongoose ODM
• Move to Elasticsearch
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4. What we will not cover:
• Scaling MongoDB
• High load volume and QPS
• Using MongoDB for analytics
• MongoDB Production/Development Deployments
• Big Data.
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5. Quick API development using MongoDB
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6. What’s your next play?
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7. 7

8. • Internal Learning Platform for LinkedIn employees
• Aggregates LinkedIn and 3rd party content
• Curated by content team for specific roles at LinkedIn
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11. 11

12. What technologies should we use?
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13. How do we leverage our current knowledge?
13

14. What server and database?
14

15. How did we build this… quickly?
15

16. Let’s start with server selection… which one?
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17. 17

18. Node.js
• Server-side JavaScript
• Lightweight and quick to setup
• NPM package support
• Extensive documentation and community
• Allows for data-driven JSON template rendering
• Easy REST API creation using Express.js
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19. Which database?
19

20. LearnIn’s Database Needs
• Support 5,000+ employees, globally
• Minimal data storage needs
• Many more reads that writes
• Able to scale with company growth
• Flexibility
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21. 21

22. MongoDB
• Easy to setup
• NoSQL with JSON structure
• Advanced querying
• Flexible schema, schema-less
• Extensive documentation
• High Single instance thresholds
22

23. 23

24. {
“data”: “have”,
“models”: “schema”
}
24

25. mongoose
25

26. Mongoose
• Object Document Mapper with easy type casting
• Quick to setup
• Easy document modeling and field validation API
• Business logic hooks, Custom Middleware
• Mongo _id reference population
26

27. var mongoose = require(‘mongoose’),
!
connection = mongoose.connect('mongodb://localhost:27017/test');
27

28. var mongoose = require(‘mongoose’),
Schema = mongoose.Schema
!
!
function BaseSchema() {
Schema.apply(this, arguments);
this.add({
publisher: {
type: ObjectId,
ref: 'User'
}
});
}
Document Modeling & Validation
var AssetSchema = new BaseModel.BaseSchema({
title: {
type: String,
required: true,
trim: true
},
description: {
type: String,
required: true,
trim: true
}
},{
collection: 'assets'
});
28

29. this.pre('save', function (next) {
if ( !this.publisher ) {
this.publisher = this.lastUpdatedByUser;
}
// Continue on to next function in queue
next();
});
Business Logic Hooks
29

30. function queryAssets(query, callback) {
model
.find(query) // query is JSON object
.populate(‘publisher’) // populate publisher from ‘users’ collection
.exec(function (error, resultSet) {
return callback && callback(error, resultSet);
});
}
NoSQL Reference Population
30

31. Our Schema Design with Mongoose
Normalized Data Modeling
Many-to-many relationships
Collection per data type
31

32. var AssetSchema = new BaseModel.BaseSchema({
title: {
type: String,
required: true,
trim: true
},
type: {
type: String,
default: 'general',
enum: typeEnums
},
relatedAssets: [
{
type: ObjectId,
ref: 'Asset'
}
]
}, {
collection: 'assets'
});
32

33. CourseSchema = new BaseModel.BaseSchema({
groups: [
{
title: {
type: String
},
items: [
{
asset: {
type: ObjectId,
ref: 'Asset'
},
task: {
type: ObjectId,
ref: 'Task'
}
}
]
}
]
}, {
collection: 'courses'
});
// nested population
function getCourseById(id, callback) {
Model
.findById(id)
.populate('groups.items.asset groups.items.task’)
.exec(callback);
}
33

34. function getAsset(req, res) {
if (!req.params.id) {
return res.send(500, 'Please add a asset ID.');
}
assetModel.model.findOne({
_id: req.params.id
}).populate('relatedAssets').exec(function (err, asset) {
if(err){
res.send(500, err);
return;
}
res.json(200, asset);
});
}
app.get('/api/asset/:id', controller.getAsset);Route:
Controller:
34

35. 35

36. 36

37. { "_id" : ObjectId("51c0b755d292ad5a7a000039"), "academy" : "Leadership", "dateCreated" : ISODate("2013-06-18T19:39:01Z"), "date_es_indexed" : ISODate("2014-02-07T16:35:00.173Z"),
"description" : "We'll discuss what is required to work in a global context at LinkedIn and how managers can become effective global leaders? ", "image_url" : "/media/images/comingsoon/
thumbnails_coming-soon3.jpg", "longdescription" : "What is required to work in a global context at LinkedIn? What are the personal capabilities that enable a global manager to succeed? How
do managers begin to develop a global perspective that will enable them to become effective global leaders? Please come prepared to discuss the following questions:nn(a) In your job, what
will you be doing differently to reflect the global nature of our business?n(b) What are some things we do as a company that still take a US-centric approach, and what would you recommend
we do to change that?", "state" : "draft", "tag_suggest" : { "input" : [ "Management & Leadership" ] }, "tags" : [ "Management & Leadership" ], "title" : "Think Global with Arvind Rajan", "type" :
"slideshow" }
{ "_id" : ObjectId("51c0b755d292ad5a7a00003a"), "academy" : "Leadership", "dateCreated" : ISODate("2013-06-18T19:39:01Z"), "date_es_indexed" : ISODate("2014-02-07T16:35:00.173Z"),
"description" : "We'll discuss how to handle difficult conversations with employees regarding performance or not meeting expectations", "image_url" : "/media/images/comingsoon/
thumbnails_coming-soon3.jpg", "longdescription" : "We'll discuss how to handle difficult conversations with employees regarding performance or not meeting expectations", "state" : "draft",
"tag_suggest" : { "input" : [ "Management & Leadership" ] }, "tags" : [ "Management & Leadership" ], "title" : "Handling Difficult Conversations with Cliff Rosenberg", "type" : "slideshow" }
{ "_id" : ObjectId("51c0b755d292ad5a7a00003b"), "academy" : "Leadership", "adder" : "", "applyContent" : "", "author" : "", "clicks" : 8, "dateCreated" : ISODate("2013-06-18T19:39:01Z"),
"date_es_indexed" : ISODate("2014-02-07T16:35:00.173Z"), "description" : "Containing vital performance and career lessons for managers at every level; this book presents the remarkable
findings of Gallup's massive in-depth study of great managers across a wide variety of situations.", "enableEnrichedAsset" : false, "image_url" : "/media/images/learningassets/leadership/
12.jpg", "longdescription" : "(b) What are some things we do as a company that still take a US-centric approach, and what would you recommend we do to change that?", "practiceContent" : "",
"state" : "live", "tag_suggest" : { "input" : [ "Editor", "Leadership & Management", "Books & Articles", "Transitioning to Management", "Management & Leadership" ] },
"tags" : [ "Editor", "Leadership & Management", "Books & Articles", "Transitioning to Management", "Management & Leadership" ], "thinkContent" : "", "title" : "First, Break All
the Rules: What the World's Greatest Managers Do Differently", "type" : "book", "url" : "https://linkedin.okta.com/app/template_saml_2_0/k2bnhvkoMCFSHKCKIJUA/sso/saml?
RelayState=https%3A%2F%2Flinkedin.skillport.com%2Fskillportfe%2Fcustom%2Flogin%2Flinkedin%2Flogin.action%3Fcourseaction%3DLaunch%26assetid%3D_ss_book%3A15501" }
{ "_id" : ObjectId("51c0b755d292ad5a7a00003c"), "academy" : "Leadership", "dateCreated" : ISODate("2013-06-18T19:39:01Z"), "date_es_indexed" : ISODate("2014-02-07T16:35:00.173Z"),
"description" : "We'll discuss the FCS model for managing hyper-growth. Fewer things done better. Communicating the right information to the right person at the right time.", "image_url" : "/
media/images/comingsoon/thumbnails_coming-soon3.jpg", "longdescription" : "We'll discuss the FCS model for managing hyper-growth. Fewer things done better. Communicating the right
information to the right person at the right time.", "state" : "draft", "tag_suggest" : { "input" : [ "Management & Leadership" ] }, "tags" : [ "Management & Leadership" ], "title" : "Managing Hyper-
growth with Jeff Weiner", "type" : "slideshow" }
{ "_id" : ObjectId("51c0b755d292ad5a7a00003d"), "academy" : "Leadership", "adder" : "", "applyContent" : "", "author" : "", "clicks" : 24, "dateCreated" : ISODate("2013-06-18T19:39:01Z"),
"date_es_indexed" : ISODate("2014-02-07T16:35:00.173Z"), "description" : "David shares learnings from the leaders that have inspired him and examples from his own career. ",
"enableEnrichedAsset" : false, "image_url" : "/media/images/learningassets/leadership/43.jpg", "longdescription" : "David shares learnings from the leaders that have inspired him and
examples from his own career. ", "practiceContent" : "", "recommendations" : [ ObjectId("521e6fd66f13a29715000044") ], "state" : "live", "tag_suggest" : { "input" : [ "Editor", "Leadership &
Management", "Videos", "Leadership 101", "Leaders Teaching Leaders", "LTL", "Management & Leadership" ] }, "tags" : [ "Editor", "Leadership & Management",
"Videos", "Leadership 101", "Leaders Teaching Leaders", "LTL", "Management & Leadership" ], "thinkContent" : "", "title" : "Leadership 101 with David Henke", "type" :
"video", "url" : "http://innertube.linkedin.biz/video/Leadership101_2013_0118/index.html" }
{ "_id" : ObjectId("51c0b755d292ad5a7a00003e"), "academy" : "Professional", "author" : "EMEA", "dateCreated" : ISODate("2013-06-18T19:39:01Z"), "date_es_indexed" :
ISODate("2014-02-07T16:35:00.173Z"), "description" : "Learn how to apply tips and tools for using your time more efficiently, meeting deadlines and increasing productivity, including learning
how to use MS Outlook more effectively.nn", "image_url" : "/media/images/learningassets/professional/36_time_management.jpg", "longdescription" : "long description", "options" :
[ "hidden" ], "state" : "draft", "tag_suggest" : { "input" : [ "Professional Development", "Learning Programs & Classes" ] }, "tags" : [ "Professional Development", "Learning Programs &
Classes" ], "title" : "Time Management ", "type" : "article", "url" : "https://linkedin.okta.com/app/template_saml_2_0/k166h5vsMZMIUWGSDZSJ/sso/saml?RelayState=%2fdeeplink
%2fssodeeplink.aspx%3fmodule%3dtranscript%26loid%3d919c0d74-4d51-43bd-87c9-546896287d49" }
{ "_id" : ObjectId("51c0b755d292ad5a7a000039"), "academy" : "Leadership", "dateCreated" : ISODate("2013-06-18T19:39:01Z"), "date_es_indexed" : ISODate("2014-02-07T16:35:00.173Z"),
"description" : "We'll discuss what is required to work in a global context at LinkedIn and how managers can become effective global leaders? ", "image_url" : "/media/images/comingsoon/
thumbnails_coming-soon3.jpg", "longdescription" : "What is required to work in a global context at LinkedIn? What are the personal capabilities that enable a global manager to succeed? How
do managers begin to develop a global perspective that will enable them to become effective global leaders? Please come prepared to discuss the following questions:nn(a) In your job, what
will you be doing differently to reflect the global nature of our business?n(b) What are some things we do as a company that still take a US-centric approach, and what would you recommend
How do we search?
37

38. > db.collection.find({ title: new RegExp(‘<search query>’, ‘i’) });
38

39. Full-Text Search
39

40. 40
> db.collection.ensureIndex({ <field>: “text" })

41. 41
> db.collection.find({ $text: { $search: <string> } });

42. • Easy searching by creating a MongoDB index
• Relevancy scoring
• Stemming and multi-language support
What text search gives us:
42

43. • Single tokenizer/analyzer
• Simple relevancy scoring, but not using Lucene
• No completion suggestion
• No fuzzy matching
• No related item search
Some limitations…
43

44. What we needed:
• Lucene index relevancy scoring and performance
• Custom field analyzers for tokenization and stemming
• ‘Related to’ or ‘More like this’ querying
• Quick completion suggestions
• Complicated wildcard searching
• Easy Node.js integration
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46. 46
?

47. elasticsearch-river-mongodb
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48. How does it work?
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49. Replica Set
OpLog
Primary
Secondary Replica
Index
ES River
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50. Configuring the River
$ curl -XPUT “localhost:9200/_river/<RIVER_NAME>/_meta” -d ‘
{
"type": "mongodb",
"mongodb": {
"servers": [
{
"host": "< HOST >",
"port": "< PORT >"
}
],
"db": "learnin",
"options": {
"import_all_collections": "true"
}
},
"index": {
"name": "prodindexnew"
}
}’
50

51. http://localhost:9200/index/type/_search?q=<search>
51

52. elasticsearch.js
52

53. Some limitations…
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54. 54

55. mongoose
LearnIn API
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57. Contact
linkedin.com/in/rseamons
!
@ryanseamons
linkedin.com/in/dejno
!
@dejno
Jacob Dejno
Web Developer
Ryan Seamons
Product Manager
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58. Questions?
58

59. Appendix
• MongoDB NoSQL Database
• Mongoose ODM
• Node.js server
• Express.js WebApp Framework
• MongoDB Full-Text Search
• Elasticsearch
• Elasticsearch-River-MongoDB
• Elasticsearch Rivers
• These Slides
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60. ©2014 LinkedIn Corporation. All Rights Reserved.
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